Induction cure of adhesives is used in situations where an adhesive is applied to an area which is difficult to heat by conventional oven baking techniques. In automobiles and trucks such an area is a flanged fixture such as a reinforcing plate for an automotive body panel. An induction coil operating with a high electrical frequency is brought into close proximity to the flanged fixture. The instantaneous heating effect raises the metal surface temperature to 150.degree. C. or above to initiate cure of the adhesive. Cure time can vary from about 4 to 45 seconds, depending on the heat generated and the cure rate of the adhesive used.
Induction cure is viewed as a viable option to spot welding because metal finishing is minimal and soundness of the bonded fixture virtually eliminates corrosion, squeaks, and rattles associated with spot welds.
Major drawbacks to induction-cured adhesives of the prior art include poor long term stability due to catalysts which are too reactive, variability in performance, and the high cost of both adhesives and suitable catalysts.
There is a need, therefore, to develop a catalyst and a curable composition containing such a catalyst with a suitable degree of reactivity for use in an induction cure adhesive which overcomes the drawbacks of the prior art.